1. Field of the Invention
Embodiments of this invention relate to a breaking composition for controlled breaking of borate cross-linked fracturing fluids, and to method for making and using same.
More particularly, embodiments of this invention relate to a breaking composition for controlled breaking of borate cross-linked fracturing fluids, and to method for making and using same, where the composition includes an oxidative component and an ester component.
2. Description of the Related Art
One of the key problems in the use of slick water, linear gels and cross-linked fluids for stimulation and fracturing applications is to find a composition and/or method that controllably breaks such polymer viscosified systems at bottom hole conditions. The ideal breakers are those that are in a liquid state and can be delivered under controlled or controllable conditions sufficient to reduce a down hole fluid viscosity to a desired low value during a formation stimulation, i.e., for a time not shorter than and not much longer than a time needed to complete the formation stimulation.
There are many effective oxidative breakers, acid breakers, terpenes breaker and enzymes breaker or combination thereof either in the form of a pure material, a solution, a suspension or an encapsulated form that most of the time break the fluid in shorter or longer periods of time than needed to complete the formation stimulation. These breakers are only effective in narrow ranges of temperatures, which are not necessarily identical to or similar to bottom hole conditions. These systems have been introduced and widely used by services companies including Halliburton, Shlumberger, BJ Services, Weatherford, Mich., Baroid, Baker Hughes, among others.
U.S. Pat. No. 5,413,178 disclosed a composition and method for breaking polymer viscosified fluids using an alkali metal chlorite or hypochlorite, which releases oxygen chloride in a controllable manner to break down the polymer structure, and, therefore, decrease the viscosity of the polymer viscosified fluids.
Historically, breaking of the borate cross-linked fracturing fluids was based on either oxidative breakers introduced by Halliburton, Schlumberger and BJ Services or more recently enzymes and esters breakers introduced by BJ Services.
U.S. Pat. No. 5,067,566 disclosed the use of esters that slowly hydrolyzes producing acids therefore when combined with enzymes favors the enzymatic degradation of the galactommana at pH lower than 9.0. U.S. Pat. No. 5,413,178 disclosed the use of chlorite and hyprchlorite systems as oxidative breakers for stabilized viscosified fluids.
Although there are numerous breaking composition for use with borate cross-linked fracturing fluids, there is still a need in the art for new breaking systems, especially breaking systems for borate fracturing fluids producing less residuals and reducing re-healing when the temperature or pH is reduced.